<!DOCTYPE html>
<style>
  #iframe {
    height: 500px;
    width: 500px;
    background-color: blue;
    border-style: solid;
    border-radius: 50px;
    border-width: 10px;
    border-color: gray;
  }
</style>
<iframe id="iframe" src="resources/subframe.html">
</iframe>
